54 PRACTICAL ORGANIC CHEMISTRY
down the middle. The filter is now pushed well into the
funnel, the stem of which is cut off short as shown at d.
A hot-water funnel is shown in Fig. 42. It consists of a
jacketed metal funnel, with a projecting metal tube. The vessel
is partly filled with water which is boiled by placing a small
burner under the end of the tube. The glass funnel is placed,
within the metal-jacket. By keeping the liquid hot, crystallisation
in the filter is thus prevented.
Before filtering an inflammable liquid such as alcohol the flame
must be removed. The potassium ethyl sulphate is dried on a
plate of unglazed earthenware or on a thin pad consisting of
three or four sheets of filter paper, with another sheet over the
crystals to keep out the dust. On concentrating the mother
liquors on the water-bath, a further quantity of crystals may be
obtained. Yield 35—40 grams. The following equations
express the chemical reactions which occur:
1. c2rrson + H2so4 = c2n5so4H + H2o
Ethyl hydrogen sulphate.
2. 2C2H5S04II + CaC03 = (C.2H5S04),Ca + HSO + C02
Calcium ethyl sulphate.
3. (CoH5S04\jCa + KX03 = 2C,ttŁO4K + CaCO3.
Potassium ethyl sulphate.
Properties. Colourless, foliated crystals ; easily soluble in
water and dilute alcohol, less soluble in. absolute alcohol.
Reactions. I. Dissolve a little of the recrystallised salt in water,
and add barium chloride solution. There is no precipitate, as
the barium salt of ethyl hydrogen sulphate is soluble in water.
2. Boil a little of the solution of the salt with a few drops
of dilute hydrochloric acid for a minute and add barium chloride.
A precipitate of barium sulphate is formed, as, on boiling ethyl
hydrogen sulphate in aqueous solution, it is decomposed into
sulphuric acid and alcohol (see Appendix, p. 234).
Ethyl Bromide (Monobromethane), C2H5Br.
De Vrij, Jahresber^ 1857, 441.
100 grms. potassium bromide,
loo j, (54 c.c.) cone, sulphuric, acid.
60 3, (75 c.c). absolute alcohol